"NameError: name 'pydal' is not defined" when function has typing type in def

[João Matos]

If I write this function

@auth.requires(lambda: (auth.requires_login() and request.env.http_referer
                        and '/client' in request.env.http_referer))
def on_delete(table: pydal.objects.Table, rec_id: str):
    """Grid delete button action.

    :param table: Table.
    :param rec_id. Record id.
    """
    if auth.has_membership(SUPERVISOR_ROLE) or auth.has_membership(MANAGER_ROLE):
        row: pydal.objects.Row = table[rec_id]
        row.update_record(cancel_approved_by=auth.user_id, canceled_by=auth.user_id,
                          canceled_on=request.now, is_active=False)
        session.flash = T('Press F5 to refresh.')
        redirect(URL(user_signature=True))
    else:
        redirect(URL('get_approval', args=[rec_id], user_signature=True))

web2py/Python show this error

    def on_delete(table: pydal.objects.Table, rec_id: str):
NameError: name 'pydal' is not defined

What is even stranger is that inside the same function there is this command
row: pydal.objects.Row = table[rec_id]
and web2py/Python don't show any error, which means they recognize pydal.

Windows 7 Pro x64 SP1+all updates
Firefox 65.0.2 x64
Python 3.7.1 x86
web2py 2.18.3

[Leonel Câmara]

Note that requires_login is meant to be used as a decorator, you should be using auth.is_logged_in()

Did you import pydal?

[João Matos]

Didn't know that, will correct auth.requires_login with auth.is_logged_in.

No I did not import pydal.

If I remove the type specification from the function header it works, even when I'm also mentioning pydal inside the function in the line

 row: pydal.objects.Row = table[rec_id]

which means pydal is imported by web2py.

[Leonel Câmara]

Weird because that doesn't work for me if I don't import pydal so I'm guessing you have a import pydal.objects.Row somewhere in your models. That said you can just use DAL.Table and DAL.Row which are imports web2py does make for you.

[João Matos]

No, I don't import pydal.objects.Row anywhere in my modules, controllers even in models.

[João Matos]

Just for testing, I removed pydal.objects.Table from the function header and changed the line inside the function from

row: pydal.objects.Row = table[rec_id]

to

row: pydal.objects.Table = table[rec_id]

without importing anything from pydal or pydal.objects, anywhere in controllers, models or modules.

And it worked without any problem.

My conclusion is that either web2py is importing pyday.objects automatically inside the function, but not when it calls (loads) the function, or web2py is not showing the errors inside the function.

Any thoughts?

sexta-feira, 8 de Março de 2019 às 17:40:41 UTC, Leonel Câmara escreveu:

[Leonel Câmara]

web2py doesn't do that. This is weird. Both those lines should give you errors.

[João Matos]

I'm using Python 3.7.1. Can that explain this strange situation?

I'm calling web2py with the -e command line option to see the errors and there are none.

[João Matos]

Apparently when importing the module, pydal is not loaded, but when running the function it is.
Is this the correct behavior of web2py?

[Massimo Di Pierro]

I do not understand. this:

row: pydal.objects.Row = table[rec_id]

is not a valid Python code. Also, as you say pydal is not imported. Moreover Row is an internal class, you should not try redefine it.

Can you explain what you are trying to achieve? Maybe there is a better way.

[João Matos]

This is valid Python code.

table and rec_id are defined in the on_delete function arguments (it's the function used in the ondelete argument of a grid).

    def on_delete(table: pydal.objects.Table, rec_id: str):

row is the variable name.

pydal.objects.Row is the variable type.

I'm using Python 3.7.1 and using Python typing.

What I'm doing is reading a single record passed by the grid's ondelete.

pydal is not auto imported by web2py when the function is defined, but it is auto imported by web2py when the function runs, because If I remove the typing from the function header, but keep the typing from the function body, everything works.

My question is if this is web2py correct behavior (pydal is not auto imported by web2py when the function is defined, but it is auto imported by web2py when the function runs).

[Massimo Di Pierro]

Can you please post a minimalist project that produces the error you are seeing?

[João Matos]

import pydal is required so that the function on_delete definition
with the pydal.objects.Table typing doesn't return an error.

This normal Python behavior.

But because I was assuming that web2py would import pydal automatically, I

detected that the import pydal isn't needed for the pydal.objects.Row typing

inside the function.


Created a new app with a single user.

File c:\web2py\applications\test\controllers\default.py

# -*- coding: utf-8 -*-

# import pydal


def index():
    db.test.is_active.readable = True

    grid: DIV = SQLFORM.grid(db.test, ondelete=on_delete)
    return dict(grid=grid)


# def on_delete(table: pydal.objects.Table, rec_id: str):
def on_delete(table, rec_id: str):

    row: pydal.objects.Row = table[rec_id]

    row.update_record(is_active=False)
    session.flash = T('Done. Press F5 to refresh.')
    redirect(URL(user_signature=True))


# ---- Action for login/register/etc (required for auth) -----
def user():
    """
    exposes:
    http://..../[app]/default/user/login
    http://..../[app]/default/user/logout
    http://..../[app]/default/user/register
    http://..../[app]/default/user/profile
    http://..../[app]/default/user/retrieve_password
    http://..../[app]/default/user/change_password
    http://..../[app]/default/user/bulk_register
    use @auth.requires_login()
        @auth.requires_membership('group name')
        @auth.requires_permission('read','table name',record_id)
    to decorate functions that need access control
    also notice there is http://..../[app]/appadmin/manage/auth to allow administrator to manage users
    """
    return dict(form=auth())

# ---- action to server uploaded static content (required) ---
@cache.action()
def download():
    """
    allows downloading of uploaded files
    http://..../[app]/default/download/[filename]
    """
    return response.download(request, db)

File c:\web2py\applications\test\views\default\index.html

{{extend 'layout.html'}}

{{=grid}}

File c:\web2py\applications\test\models\db.py

# -*- coding: utf-8 -*-

# -------------------------------------------------------------------------
# AppConfig configuration made easy. Look inside private/appconfig.ini
# Auth is for authenticaiton and access control
# -------------------------------------------------------------------------
from gluon.contrib.appconfig import AppConfig
from gluon.tools import Auth

# -------------------------------------------------------------------------
# This scaffolding model makes your app work on Google App Engine too
# File is released under public domain and you can use without limitations
# -------------------------------------------------------------------------

if request.global_settings.web2py_version < "2.15.5":
    raise HTTP(500, "Requires web2py 2.15.5 or newer")

# -------------------------------------------------------------------------
# if SSL/HTTPS is properly configured and you want all HTTP requests to
# be redirected to HTTPS, uncomment the line below:
# -------------------------------------------------------------------------
# request.requires_https()

# -------------------------------------------------------------------------
# once in production, remove reload=True to gain full speed
# -------------------------------------------------------------------------
configuration = AppConfig(reload=True)

if not request.env.web2py_runtime_gae:
    # ---------------------------------------------------------------------
    # if NOT running on Google App Engine use SQLite or other DB
    # ---------------------------------------------------------------------
    db = DAL(configuration.get('db.uri'),
             pool_size=configuration.get('db.pool_size'),
             migrate_enabled=configuration.get('db.migrate'),
             check_reserved=['all'])
else:
    # ---------------------------------------------------------------------
    # connect to Google BigTable (optional 'google:datastore://namespace')
    # ---------------------------------------------------------------------
    db = DAL('google:datastore+ndb')
    # ---------------------------------------------------------------------
    # store sessions and tickets there
    # ---------------------------------------------------------------------
    session.connect(request, response, db=db)
    # ---------------------------------------------------------------------
    # or store session in Memcache, Redis, etc.
    # from gluon.contrib.memdb import MEMDB
    # from google.appengine.api.memcache import Client
    # session.connect(request, response, db = MEMDB(Client()))
    # ---------------------------------------------------------------------

# -------------------------------------------------------------------------
# by default give a view/generic.extension to all actions from localhost
# none otherwise. a pattern can be 'controller/function.extension'
# -------------------------------------------------------------------------
response.generic_patterns = []
if request.is_local and not configuration.get('app.production'):
    response.generic_patterns.append('*')

# -------------------------------------------------------------------------
# choose a style for forms
# -------------------------------------------------------------------------
response.formstyle = 'bootstrap4_inline'
response.form_label_separator = ''

# -------------------------------------------------------------------------
# (optional) optimize handling of static files
# -------------------------------------------------------------------------
# response.optimize_css = 'concat,minify,inline'
# response.optimize_js = 'concat,minify,inline'

# -------------------------------------------------------------------------
# (optional) static assets folder versioning
# -------------------------------------------------------------------------
# response.static_version = '0.0.0'

# -------------------------------------------------------------------------
# Here is sample code if you need for
# - email capabilities
# - authentication (registration, login, logout, ... )
# - authorization (role based authorization)
# - services (xml, csv, json, xmlrpc, jsonrpc, amf, rss)
# - old style crud actions
# (more options discussed in gluon/tools.py)
# -------------------------------------------------------------------------

# host names must be a list of allowed host names (glob syntax allowed)
auth = Auth(db, host_names=configuration.get('host.names'))

# -------------------------------------------------------------------------
# create all tables needed by auth, maybe add a list of extra fields
# -------------------------------------------------------------------------
auth.settings.extra_fields['auth_user'] = []
auth.define_tables(username=True, signature=True)

# -------------------------------------------------------------------------
# configure email
# -------------------------------------------------------------------------
mail = auth.settings.mailer
mail.settings.server = 'logging' if request.is_local else configuration.get('smtp.server')
mail.settings.sender = configuration.get('smtp.sender')
mail.settings.login = configuration.get('smtp.login')
mail.settings.tls = configuration.get('smtp.tls') or False
mail.settings.ssl = configuration.get('smtp.ssl') or False

# -------------------------------------------------------------------------
# configure auth policy
# -------------------------------------------------------------------------
auth.settings.registration_requires_verification = False
auth.settings.registration_requires_approval = False
auth.settings.reset_password_requires_verification = True

# -------------------------------------------------------------------------
# read more at http://dev.w3.org/html5/markup/meta.name.html
# -------------------------------------------------------------------------
response.meta.author = configuration.get('app.author')
response.meta.description = configuration.get('app.description')
response.meta.keywords = configuration.get('app.keywords')
response.meta.generator = configuration.get('app.generator')
response.show_toolbar = configuration.get('app.toolbar')

# -------------------------------------------------------------------------
# your http://google.com/analytics id
# -------------------------------------------------------------------------
response.google_analytics_id = configuration.get('google.analytics_id')

# -------------------------------------------------------------------------
# maybe use the scheduler
# -------------------------------------------------------------------------
if configuration.get('scheduler.enabled'):
    from gluon.scheduler import Scheduler
    scheduler = Scheduler(db, heartbeat=configuration.get('scheduler.heartbeat'))

# -------------------------------------------------------------------------
# Define your tables below (or better in another model file) for example
#
# >>> db.define_table('mytable', Field('myfield', 'string'))
#
# Fields can be 'string','text','password','integer','double','boolean'
#       'date','time','datetime','blob','upload', 'reference TABLENAME'
# There is an implicit 'id integer autoincrement' field
# Consult manual for more options, validators, etc.
#
# More API examples for controllers:
#
# >>> db.mytable.insert(myfield='value')
# >>> rows = db(db.mytable.myfield == 'value').select(db.mytable.ALL)
# >>> for row in rows: print row.id, row.myfield
# -------------------------------------------------------------------------

db.define_table('test',
                Field('code', 'string', label=T('Code'), notnull=True,
                      required=True, unique=True),
                auth.signature,
                )

# -------------------------------------------------------------------------
# after defining tables, uncomment below to enable auditing
# -------------------------------------------------------------------------
# auth.enable_record_versioning(db)

[Massimo Di Pierro]

I honestly do not know. I do not think this is a web2py specific issue. Definitively  pydal is already imported but the name is not defined in the controller's scope. Do not know how the interpreter handles the type annotation or where it looks them up.